Containers made of corrugated paperboard are commonly used for storing and shipping agricultural produce. Typically, such containers are formed from a blank scored with score lines and cut lines and have a bottom and opposed sidewalls. As used herein, the term “sidewalls” refers to the side walls extending along opposite sides of a container and the end walls extending across opposite ends of a container. The term “side wall” or “end wall” is used when a particular wall is intended. The blanks are most often formed by automated machines in a continuous in-line process involving cutting, scoring and molding continuous sheets of paperboard. The paperboard is then folded along the score lines and cut lines to form a container. The blanks may be folded into a container by an automated machine or may be set up by hand.
Conventional containers used within many produce segments typically comprise three-piece Bliss style cartons. These container designs have to be run over two different machines at the box plants, requiring extra manpower to run the machines, and they require extra warehousing for the three pieces and extra labor for set-up at the customer's locations.
During use, containers are often stacked on top of one another for ease of shipping and for optimum use of space. For stability in stacking the containers it is common to have stacking tabs extending upward from the top edge of the container sidewalls. These stacking tabs often fit into corresponding notches cut into a superjacent container to help secure the stack. Since containers are usually stacked on top of like-sized containers, the stacking tabs that extend upwardly from a lower container are positioned directly into the sidewalls of a superjacent container. Thus, to accommodate the stacking tabs on a lower container, a complementary notch must be cut out of the bottom edge of the sidewall of a higher container. However, a notch in a sidewall is problematic in that it does not secure the stacking tab on all four sides. Thus, these sidewall notches do not fully prevent side-to-side movement, subjecting the stack to potential toppling. This is sometimes circumvented by having a multi-ply or multi-layer sidewall, wherein a stacking tab extends upwards from an inner layer of the sidewall, thereby aligning the stacking tabs with the bottom panel of an adjacent container as opposed to the sidewall. This, however, requires excess paperboard to be used to create the multi-layer sidewall, and results in related increased costs.
Further, it is easy to misalign a container during stacking such that a higher container falls into a lower container, usually on an angle, potentially damaging the contents of the lower container. To solve this, several prior art containers have been designed with inwardly inclined sidewalls, wherein the distance between the opposing top edges of the sidewalls is less than the distance between the opposing lower edges of the sidewalls. This eases stacking by severely limiting the probability of the higher container falling into a lower container, since the narrower upper portion creates a more functional ledge for the base of the higher container to rest on.
Some prior art containers have reinforcing corner posts to increase their stacking strength and to assist in preventing an upper container from falling into a lower container when they are stacked, but applicant is not aware of any prior art container that has both full depth reinforcing corner posts and inclined side walls with stacking tabs. One prior art container with inclined side walls has diagonally extending reinforcing corner panels at the upper margin of the container, but these panels do not extend the full height of the container.
Other prior art containers have full depth reinforcing corner posts to increase stacking strength, but they do not have inclined sidewalls.
Applicant is not aware of any prior art paperboard container that has inclined sidewalls, stacking tabs, and full height reinforcing corner posts, and especially such a structure wherein panels extending from opposite ends of the sidewalls are folded to form the corner posts and include sections adhered to adjacent portions of the side walls and end walls.